Minimization of structure-borne sound and vibration isolation in wheel-track systems by the Civicell and Ciplacell microcellular, high-tech EPDM elastomers.
Requirements
When trains pass by, the moving load, the roughness of the wheels and rails as well as local variations in the strength of the track system cause vibrations and structure-borne noise. High-frequency effects are primarily caused by interactions between the vehicle and the track (lack of roundness of the wheels, corrugations, defects in track geometry, slip waves etc.), as well as low-frequency impacts on axle loads, driving speed, and distances between coaches, axles and bogeys. This largely characterizes the load on the overall system. Through the use of highly elastic materials – such as microcellular EPDM, and natural rubber and CR composite materials in particular – from Calenberg-Ingenieure in superstructures that are optimized to combat vibration, the transfer of vibrations to the substructure can be limited effectively and permanently.
(Excerpt from a test report in compliance with DBS 918235: 2017)
Our elastomeric bearings for rail fastening systems optimally and sustainably meet the requirements for modern track systems. With our elastomers for highly elastic intermediate plates and layer pads, which are made of microcellular EPDM and have a very wide range of spring rigidity to minimize structure-borne noise due to track vibrations, we make a major contribution towards reducing the load on the superstructure of the track, which protects the overall superstructure of the system and thus greatly reduce the costs for maintenance and service for our customers.
(Axle load – wheel load – base load)
The solution
With the use of elastic or highly elastic intermediate layers and intermediate plates in special SBS, the load-transferring effect of the rail is used and the forces occurring are distributed to several points of support of the applied wheel load, so that the load on the rail support point that is directly affected is greatly reduced.
System 300-1 with highly elastic intermediate plate Zwp 104 NT – 22.5 EPDM Ciplacell
Noise is also a manifestation of frictional resistance and unevenness, corrugation, slip waves etc. and the vibrations these generate when rail vehicles pass over. Noise is reduced to a minimum if the railway vehicle and railway tracks are in good working order.
The influence of high-frequency vibrations, which are transferred via the track through the sleepers into the ballast bed, is greatly reduced by the use of elastic intermediate layers, which counteracts destruction of the ballast.
Outstanding characteristics of microcellular EPDM elastomers (closed pore) from Calenberg Ingenieure
- Very high rebound resilience (> 60%), (is immediately ready again for the next wheel)
- Outstanding structure-borne sound insulation
- Minimal water absorption – due to entirely closed-pore foam
- Comparatively small change in the spring coefficient in the operating temperature range [-40 (-40 °F) to +100 °C (212 °F)]
- Outstanding age- and weather-resistance
- Excellent UV and ozone stability (saturated molecular chain)
- Low frequency dependence between 1 Hz and 30 Hz (dynamic stiffening – stiffening factor approx. 1.1)
- Excellent resistance to hydrolysis (water, aqueous solutions with lyes, thawing salts, acids, detergents)
EPDM elastomers contain a saturated polymer backbone in their chemical structure that provides high stability against a variety of chemical attacks. This explains the properties of the material with regard to temperature, aging and weathering, as well as its excellent resistance to polar media.
An adjustable spring stiffness, as defined according to the customer’s requirements, as well as the degree of foaming in the pore structure and number of pores in closed-cell foamed design is possible at any time. The visible vulcanization membrane protects the highly elastic bearings against mechanical influences on their surface.
If you have any questions or suggestions, please do not hesitate to contact the relevant technical department.